Is 4x^2+y^2+16x-6y+9=0 a parabola, a circle, an ellipse, or a hyperbola?

1 Answer
May 11, 2018

An ellipse with vertical major axis.

Explanation:

4x2+y2+16x6y+9=0

Convert to standard form by completing the square:

4x2+16x+y26y=9

4(x2+4x+4)+(y26y+9)=9+16+9

4(x+2)2+(y3)2=16

(x+2)24+(y3)216=1

Equation of an ellipse with vertical major axis in standard form:
(xh)2a2+(yk)2b2=1
Where:
(h,k) is the coordinate of the center
2b is the major axis

So in this case:
Center is at (2,3)
a=2,b=4
Major axis is along the y-axis and the length is: 8